Download Remote Access VPN IPsec

Application Note
Remote access VPN IPsec
Accessing the MRD-3xx Indsutrial 3G router using TheGreenBow IPSec VPN Client
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Application Note
IPsec VPN
A virtual private network (VPN) is a private data network that makes use of the public
telecommunication infrastructure, maintaining privacy through the use of a tunnelling protocol and
security procedures. A virtual private network can be contrasted with a system of owned or leased
lines that can only be used by one company. The main purpose of a VPN is to give the company
the same capabilities as private leased lines at much lower cost by using the shared public
infrastructure. Phone companies have provided private shared resources for voice messages for
over a decade. A virtual private network makes it possible to have the same protected sharing of
public resources for data.
IPsec is a suite of protocols for providing peer authentication without transmitting the actual keys.
Confidentiality using encryption and integrity ensuring that the received data can only come from
the authenticated peer and has not been altered in any way.
IPsec Encrypting Security Payload tunnels also provide transparency for all nodes and
applications using IP and only the VPN gateways needs to be configured to securely connect
geographically separated networks.
Firstly we will describe and determine all the parameters necessary for this configuration. These
values will be written into the “IPsec Network setup table”
The numbers and parameter values from the “IPsec Network setup table” will be used throughout
this guide while first configuring the responder and then the initiator.
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Application Note
Network setup description
This application note describes how to implement a Remote access IPsec VPN tunnel between
TheGreenBow IPsec VPN Client and a Westermo MRD-330 Industrial 3G Router.
TheGreenBow IPsec VPN Client will probably have a dynamically assign IP address and may or may
not be behind a Network Address Translation (NAT) device. As such we must assume that we need
NAT traversal and TheGreenBow will be the initiator.
In this example the MRD-330 has a 3G subscription that provides a static public IP address. Since we
want to access the MRD-330 it has to be the responder.
For authentication we will be using Pre-Shared Key (PSK). Simple and practical for initial and smallscale VPN configurations it is however very susceptible to social engineering and large scale or longterm deployment should use certificates for authentication.
This IPsec configuration uses Internet Key Exchange (IKEv1). If the IP addresses of both parties are
fixed or certificates are used it is recommended to use IKE main mode which takes longer to establish
connection but provides a higher level of security than aggressive mode.
In this example the combination of dynamic IP address and preshared key requires us to use IKE
aggressive mode.
IKE supports many different types of identifiers (ID). For this example we have chosen type 2 FQDN.
Please review RFC 2407 for further options.
Encapsulated Security Payload (ESP) is the final encrypted tunnel joining initiator/responder together.
An ESP tunnel is unidirectional so two tunnels are used for full duplex communication. Advanced
Encryption Standard (AES) is the recommended encryption standard to use since it is more secure
and more efficient than the older 3DES encryption.
This configuration is valid for:
TheGreenBow IPsec VPN Client 4.5
Westermo MRD-310/330 firmware version 1.11
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Application Note
IPsec Network setup table
Initiator
Responder
217.174.88.165
APN
Remote Access IPSec tunnel
Internet
10.10.10.10
192.168.33.0/24
10.10.10.20
Initiator
Responder
General
External Address IP or FQDN
1
0.0.0.0
2
217.174.88.165
Internal IP address
3
10.10.10.20
4
10.10.10.10
Internal subnet mask
5
255.255.255.255
6
255.255.255.255
ID type
7
2
8
2
ID value
9
greenbow
10
mrd330
PSK
Certificate
RFC2407
11
54321
12
13
NAT Traversal
14
YES
NAT-T keepalive
15
20s
Dead Peer Detection
16
YES
DPD delay & timeout
17
30s/15s
MTU
18
19
IKE phase 1
Mode
20
Aggressive
Encryption
21
AES (128)
Authentication
22
MD5
Diffie Hellman Group
23
2
IKE SA Lifetime
24
3600s
ESP encryption
25
AES (128)
ESP authentication
26
MD5
SA Lifetime
27
28800s
Perfect Forward Secrecy
28
2
IKE phase 2
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Application Note
Responder configuration
Make sure you have configured your MRD-3xx router as described in the User Guide.
The firewall on the MRD-330 will deny all connection attempts by default. In order for us to connect with IPsec we
must open the firewall to IKE udp ports 500 and 4500 aswell as allow ESP (IP protocol 50)
Select Firewall in the top most menu followed by Access Control in the submenu.
Select allow for IPsec VPN on the wireless interface (WLS) and press update.
Allow IPsec VPN
access
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Application Note
IPsec VPN Configuration
Make sure you have configured your MRD-3xx router as described in the User Guide. Access the routers web
interface and select VPN in the top menu followed by ”IPsec VPN” in the submenu.
Select ”Enabled” and NAT traversal followed by update.
To create a new tunnel click the
button.
14
15
18
The web interface requires a Remote host to move to the next step but since we can not know the address
we use 0.0.0.0 to indicate that the remote host can have any IP address.
We cannot access the private IP address of the initiator and as such the responder should not ”Initiate tunnel”
1
17
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Application Note
IKE phase configuration
Next we configure the authentication and proposal for Internet Key Exchange (IKE)
The ID must be preceeded with a @ sign to indicate a type 2 or 3 ID (RFC2407) string.
11
9
10
20
21
22
23
24
Phase 2 configures two ESP tunnels for the actual protected traffic. The newer less CPU intensive AES
encryption should be preferred before 3DES.
For Remote access we are using endpoint addresses or virtual hosts where the MRD-330 will have the
internal address 10.10.10.10 and the client 10.10.10.20
28
25
26
27
4
3
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Application Note
TheGreenbow VPN client configuration
TheGreenBow VPN client is available on trial from http://www.thegreenbow.com/vpn_down.html
Once installed open the configuration window and start a new phase 1.
2
11
21
22
23
Enter a gateway name and the Responder address. Preshared key and IKE encryption, authentication and
Diffie Hellman group must match what has been entered in the MRD330.
Remember to Save & Apply
Next open the ”P1 Advanced…" window and enter Local and Remote ID type and value. Select Aggressive
Mode and click OK
Remember to
20
14
7
9
10
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Application Note
Tunnel configuration
Right click on the Phase 1 entry ”MRD330" and select ”add Phase 2".
Choose a name for the tunnel and enter the virtual host IP address of both client(Initiator) and Remote
host(Responder). Select the correct Encryption, authentication and mode (tunnel).
Press ”Save & Apply”
3
4
25
26
28
Select ”Parameters” from the left side menu and enter the correct Lifetime and Dead Peer Detection values.
Press ”Save & Apply”
24
27
17
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Application Note
Diagnostics
Open TheGreenBow VPN client connection panel and press ”Open” on the MRD330-Tunnel.
Progress or errors can be viewed in TheGreenBow Console and the MRD-330 Status > Syslog.
Once connected you should be able to open the MRD-330 web interface on address 10.10.10.10
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Application Note
IPsec Network setup table
Initiator
Responder
Remote Access IPsec tunnel
APN
Internet
Initiator
Responder
General
External Address IP or FQDN
1
2
Internal IP address
3
4
Internal subnet mask
5
6
ID type
7
8
ID value
9
10
PSK
Certificate
11
12
13
NAT Traversal
14
NAT-T keepalive
15
Dead Peer Detection
16
DPD delay & timeout
17
MTU
18
19
IKE phase 1
Mode
20
Encryption
21
Authentication
22
Diffie Hellman Group
23
IKE SA Lifetime
24
IKE phase 2
ESP encryption
25
ESP authentication
26
SA Lifetime
27
Perfect Forward Secrecy
28
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Application Note
Technical Support
If you require assistance with any of the instructions in this application note you can
contact Westermo as follows:
Sweden
www.westermo.se
[email protected]
Phone: +46 (0)16 42 80 00
Fax: +46 (0)16 42 80 01
France
www.westermo.fr
[email protected]
Tél : +33 1 69 10 21 00
Fax : +33 1 69 10 21 01
United Kingdom
Web: www.westermo.co.uk
[email protected]
Telephone: +44 (0)1489 580585
Fax: +44 (0)1489 580586
Singapore
www.westermo.com
[email protected]
Phone +65 6743 9801
Fax +65 6745 0670
Germany
www.westermo.de
[email protected]
Tel: +49(0)7254 95400-0
Fax: +49(0)7254-95400-9
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